1. Field of the Invention
The present invention relates to a method for manufacturing a magnetoresistance head and, more particularly, a method for manufacturing a magnetoresistance head including a step of forming patterns by virtue of lift-off technique.
2. Description of the Prior Art
A magnetoresistance head utilized as a reproducing head of a magnetic recording apparatus has the configuration as shown in FIG. 1, for instance. The magnetoresistance head is implemented by forming sequentially a SAL (Soft Adjacent Layer) 102, a nonmagnetic layer 103, and a magnetoresistance layer (referred to as "MR layer" hereinafter) 104 on a lower gap layer 101, then patterning these three layers as a planar rectangular pattern, and then forming antiferromagnetic layers 105a, 105b and lead terminals 106a, 106b on both sides of the rectangular pattern. A region formed between two lead terminals 106a, 106b serves as a sense region S.
A pair of lead terminals 106a, 106b are formed by lift-off process, as described below with reference to FIGS. 2A to 2C.
Referring to FIG. 2A, a resist 107 is coated on the rectangular pattern of the SAL 102 one time, the nonmagnetic layer 103, and the MR layer 104 and on the lower gap layer 101. The resist 107 is then patterned by exposing and developing the resist 107 so as to expose two lead terminal forming regions and to cover the sense region S on the MR layer 104. As shown in FIG. 2B, the antiferromagnetic layer 105 and the metal film 106 are formed by sputtering. In turn, the resist 107 is released to leave the metal layer 106 only on two lead terminal forming regions. The antiferromagnetic layer 105 and the metal film 106 are thus left only on two lead terminal forming regions, which are used respectively as the antiferromagnetic layers 105a, 105b and the lead terminals 106a, 106b, as shown in FIG. 2C.
However, in the event that side portions of the patterned resist are patterned to form vertical flat surfaces, there is caused such a drawback that flashes are apt to be generated on peripheries of the lead terminals 106a, 106b.
In order to suppress such flashes of the lead terminals 106a, 106b, it has been known to use the resist having a two-layered structure.
For instance, as has been recited in U.S. Pat. No. 5,087,332 and Patent Application Publication (KOKAI) 3-125311, the resist is coated two times to prepare for patterning of the gap layer in the magnetic head, then sectional shapes of the resist are formed to have a mushroom-like sectional shape by exposing and developing the resist two times, then the resist is used as a lift-off mask. In addition, the lift-off mask having such mushroom-like sectional shape in which the upper layer and the lower layer consist respectively of the resist and the Al.sub.2 O.sub.3 film has been recited in Patent Application Publication (KOKAI) 7-65326.
However, if relative misalignment of mask positions occurs during exposure process since these masks are processed by two-time patterning, the mushroom-like sectional shapes may be unbalanced on the right and left sides, otherwise the resist may be curved because the upper resist layer has projected too much laterally. Hence it becomes difficult to improve manufacturing yield of the magnetic head.
Furthermore, there are some cases where the resist having the mushroom-like sectional shape is used commonly as the lift-off mask as well as the mask for forming the magnetic layer pattern. In this event, since the resist is damaged in the course of vacuum process, constituents of the resist such as the organic substance are scattered from the resist and stick to the surface of the magnetic layer. This causes defective contacts between the magnetic layer and the lead terminals.
In addition, if release liquid for the two-layered resist and other conditions are improper, the magnetic layer is also damaged.